In general, in order to manufacture semiconductor devices, desired devices are manufactured by performing a variety of processes such as a film deposition process, a dry etching process and the like on a substrate such as a semiconductor wafer or the like. However, a line width and a hole diameter are increasingly miniaturized to respond to requirements for further high-integration and fine-miniaturization of semiconductor devices. In fact, in recent years, wire layers have come to have complicated wiring structures such as an eight-layer structure. Furthermore, copper that has low electric resistance and low cost is likely to be used as a wiring material and a filling material because electric resistance needs to be lowered due to the miniaturization of a variety of dimensions (e.g., see Patent Document 1).
When using copper as the wiring material and the filling material, considering adhesion of copper to an under layer thereof and prevention of diffusion of copper, in general, tantalum metal (Ta), titanium (Ti), a tantalum nitriding film (TaN), a titanium nitriding film (TiN) or the like is interposed as a barrier layer.
In this regard, a description is given below with reference to FIGS. 1A and 1B. FIGS. 1A and 1B are diagrams for illustrating a part of a conventional filling process for filling a recess of an object to be processed. FIG. 1A illustrates a part of a process in the middle of forming a TSV (Through Silicon Via) structure used in mounting an integrated circuit three-dimensionally.
In the object to be processed 2 illustrated in FIG. 1A, a semiconductor device (not shown in the drawing) such as a transistor and a conductive layer 6 constituting a wiring layer of the semiconductor device are formed in a surface of a substrate 4 made of a disk-shaped silicon substrate about 0.7 mm thick, and the whole surfaces of this semiconductor device and the conductive layer 6 are covered with a protective insulating layer 8. Moreover, in the object to be processed 2, the thickness of the substrate 4 is thinned up to about 0.1 mm by grinding the back surface (back grinding) of the substrate 4; the substrate is turned upside down; and a recess 10 is formed by etching the substrate 4 from the back surface side (upper side in the drawing) to the conductive layer 6.
In the bottom of the recess 10, the conductive layer 6 is exposed. This recess 10 becomes a through-hole for contact with an extraction electrode of a semiconductor device, a via-hole for connecting interconnections with each other and the like. Moreover, in order to perform a three-dimensional mounting, the recess is filled with a copper film for conduction when a semiconductor device and the like are further formed on the upper surface side of the reversed substrate 4. In this case, prior to forming the copper film, as illustrated in FIG. 1B, an insulating film 12 is deposited on the whole surface and a whole side wall inside the recess 10 to ensure insulation properties to the substrate 4, and a barrier film 14 for preventing the copper diffusion is deposited on the insulating film 12. After that, the recess 10 is filled by depositing a filling metal film 16.
Here, for example, SiO2 film made of TEOS (Tetraethyl orthosilicate) is used as the insulating film 12. Ti, Ta, a nitriding film thereof (TiN, TaN) or the like is used as the barrier film 14. For example, a copper film is used as the filling metal film 16.
In the meantime, because of requirements of further high-integration, fine-miniaturization and high-performance of the semiconductor devices these days, the line width and the hole diameter are increasingly miniaturized and the recess has a high aspect ratio, which makes it impossible to deposit a barrier film that has sufficient barrier properties by the conventional method.
Therefore, recently, using a polymer thin film such as polyimide (resin) or the like as the barrier film 14 or an insulating film has been proposed (e.g., see Patent Documents 2 and 3). In order to form the polymer thin film, a wet process that polymerizes raw materials with each other by dissolving the raw materials in a solvent and performing spin coating and a vapor deposition polymerization that polymerizes raw materials evaporated in a vacuum atmosphere, are known.